Part of Your World
by JuHuaTai
Summary: Following the death of his brother, Marco, a pirate on his way for vengeance, found his mission intertwined with that of a sheltered, pirate-hating merman prince in search for his kingdom's stolen artefact. Along the way, it became less about their goal and more about the journey itself [Merman!AU]
1. Chapter 1

(Mermaid!AU - Title from a Little Mermaid Song. Original)

Hello, i still have writers block, but i have ideas coming out the wazoo.

If my writers block persist, i may develop this too because i'm a moron like that and my brain works in mysterious ways. You should know by now and for that i apologize.

For now, however, enjoy this out of nowhere oneshot.

Hope you'd enjoy!

* * *

"Hey birdbrain, catch,"

Marco hadn't even fully turned when a thankfully soft piece of cloth smacked him right on the face. Somewhere nearby, there's laughter, obviously from the culprit who had thrown it, and as soon as he plucked the towel away from his face, he found him doubled over in hilarity just a few feet away.

"Funny," he groused, but was thankful all the same, using the towel to wipe the sweat off from his face and neck. He didn't even realized how much he had sweated until the towel turned damp once he was done with it, before slinging it over his shoulder, "Done with dinner preparation? Usually, you'll still be up in the kitchen at this hour,"

The man didn't answer, only smiling enigmatically at him as he walked closer.

He raised a brow when their distance was close enough, standing toe to toe.

"Hey, what—"

Suddenly, the man moved closer, and gone right pass him.

* * *

Marco woke up with a gasp, and immediately shut his eyes close once more when his vision was assaulted by bright ray of sun.

Once the headache that came from the unexpected brightness passed, he let out a groan and pushed himself upward, his hand digging to rough earth while the other covered his face, wiping down lethargically. In the distance, he can hear the sound of rolling waves mingling together with the gentle caressing of plants, which jogged his memory about his current situation, as well as what led him to this particular place.

Images of his dream slowly came back to his no longer fuzzy mind, and in recollection, he took a deep breath, dropping his hand down with his eyes still closed.

Right.

It's been a month since he lost his brother, the very figure haunting him in his last dream, which means it's also been a month that he had been on the pursuit for the person who had caused it.

And it was all going smoothly, if progressing too slowly for his liking, but he had only recently receive a clue as to where his target had gone to and he had been on a chase since. He had been flying for 3 days straight without a break when he was hit by an unexpected storm, and the last thing he remembered before this very moment had been being swept away by the turbulent. So it would seem that he was carried to this place, thankfully still alive although admittedly aching just about everywhere.

Speaking of…

Where exactly is 'this'?

Blue orbs just a shade darker than the sky above blinked open, darting from corner to corner. It would seem that he's in a forest right now, in the middle of a clearing of sorts. There's fallen trees here and there, an evidence of the storm that had carried him, and if he looked beyond the thick wooden forest, he could almost perceive the wide expanse of sea just beyond, which explains where the sound of waves came from.

With another groan, he stood up, dusting his clothes and pants away from any dirt and grass. He must be way off from his original course right now, and the sad thing is, he didn't have any idea just how far away he was. The log pose should be able to tell him, but he'll need to find his belongings first, provided they hadn't been carried away somewhere else by the storm—

A low rumbling was heard from his stomach, a small sound made louder by the very palpable silence around him and Marco grimaced.

Maybe after some food.

* * *

Well, this is quite the predicament.

He didn't find his belongings, he didn't find any telltale sign of life, and more importantly, he couldn't find a single thing around that can be eaten. Worse yet, the one thing he did manage to find, his log pose, was shattered in pieces, with the needle bent beyond belief and with no chance of fixing it to at least tell him his next location. Which means even if he wanted to, Marco wouldn't know which direction to take to the nearest inhabited island.

His stomach growled again and he bit his lower lips, trudging heavily across the damp land.

By now, the sun has reached its peak position on the sky, which at least could tell him that its around mid day. He's wasting time as it is only walking around, should he take a chance and choose a random direction? Sooner or later, he'd come across someplace else, which is better than staying in one place and being continuously starving. There's not a single fruit growing on the thick foliage above his head, no fishes by the shores, absolutely nothing.

Sighing, the blonde man pushed back against thick series of bushes. He heard a stream coming from this direction earlier, maybe he can at least have something to drink first just to make sure he won't get dehydrated—

Actually, never mind. It seems like he already is and it's affecting his brain.

Because there is no other explanation as to why he's seeing not only a small waterfall which he was sure caused the sound of running water, but a large, multicoloured fin the colour of darker sunset jutting out of the jerky waves, flapping back and forth in an almost hypnotizing motion. With wide eyes, Marco approached, already feeling his mouth watering at the thought of how big the fish could possibly be and how it could immediately sate his hunger.

Once he was close enough, he braced himself, ready to transform his feet into talons in order to pierce through the regrettably beautiful scales soaked inside of the stream, when something else unexpected happened.

The fin stopped their swaying and made a sudden rush for him, hitting him by the stomach and knocking out his breath. Marco stumbled backward, surprised by the blow, but before he can even regain his balance back he was suddenly forced down by another, recognizably human body, strong hand clutching themselves around his neck and pressing against his windpipe harshly.

"Who are you?!" his assaulter shouted - there's someone else here, after all? How come he hadn't found a single sign of them beforehand? - tightening their grip around his neck, " How could a human reach these waters?"

In reply, he could only cough and sputtered as he tried to claw the hand away from choking him, only barely aware of the dripping all over his body and face, and how cold and clammy the other person's skin was against his own. With some effort, he opened his eyes, and for a second, stopped moving.

The person above him was undeniably male and naked, at least as far as he could see down his chest, with angry eyes the colour of last night's stormy sky and freckles dusted across his cheeks like the late night stars. Wet, dripping dark hair framed the youthful and aggressive sight, curled and plastered against fair skin, and even with the unsightly snarl that shows a series of oddly sharp teeth, Marco could only blink and found himself whispering, "…Beautiful,"

Dark eyes widened, as the man - boy? He looks quite young - loosened his grip around his neck and seemingly unconsciously moved back, looking as bewildered as Marco think he himself felt, "Huh?!"

But being freed from the choking grip barely registered to the dumbfounded man, as he glanced his eyes down and saw something utterly impossible.

The dark haired male was naked indeed, but instead of a pair of legs, what was attacked to his waist was an honest-to-all _tail,_ a fish tail even, the very same tail and fin that he saw earlier from the water stream. Fragile, spiked and translucent fin fanned out on the ground in a display that reminded him of the softest silk one of his brother owned, a gradient of fiery red and cheerful yellow that dipped into the darkest black trails up to the shapely tail that hit him earlier, dispersing into little dots that decorated scales the colour of setting sun against lightly tanned skin.

"You're beautiful,"

The merman's face began to colour, freckles seemingly blooming as deep red flush settled on his cheeks and he jumped back, hissing, "You— How could you reach this place? No human was ever supposed to find this location,"

He should probably answer, but Marco found himself tongue-tied, unable to even register that he's being asked a question.

A merman. Unless he's severely hallucinating right now, he's actually seeing a merman.

(Well, that explains the 'human' comment)

Nevertheless, there hasn't been a sighting of one in over centuries. Merfolk were incredibly secretive, so much so that their existence as a whole was forgotten and often thought of as a legend. The fabled kingdom of Mermen, Raftel, was the dream of every single young boys and girls, and the journey to discover them was the end goal of every pirate out roaming the 4 seas, in hopes to not only uncover the legend of the merfolk but to also gain their treasure, the famed One Piece.

And Marco just found one of those legendary creatures.

All because he's so goddamn hungry.

"Hey!' webbed fingers were snapped in front of his eyes, making him jolt out of his reverie. The blonde looked up to see those previously confused and startled eyes turning angry once more, with the snarl back stronger and more menacing than ever, "I'm talking to you! How did you get here?! No human were ever supposed to found these waters,"

"I don't even know where i am," he answered truthfully, still completely baffled by this entire turn of event. A merman. Holy shit, he's seeing, talking and almost thought of eating a merman, "I was carried by the storm,"

The merman's eyes narrowed, cocking his head over to the direction of the sky. As he does this, his tail flopped a little and his long, flowing fins made a little wave motion. Marco's gaze was instantly brought back to it, eyes unable to look away in admiration, "Storm? That storm wasn't big enough to carry a human,"

"I wasn't exactly a 'human' when it blew me here,"

Again, the merman narrowed his eyes even further in suspicion, and even without saying, Marco can practically feel his demand for him to explain, "I'm a Devil Fruit user. A phoenix zoan,"

Instead of accepting that as an answer, the freckled male kept staring at him, the edge of his tail standing up and sending his fin into a wave. It looked almost like an unconscious gesture, much like how a human would unthinkingly move their limb while thinking, and for some reason, he found that incredibly adorable.

He chuckled, standing up, "I think it's best that i just show you,"

In a blink of eye and with a burst of blue and yellow flame, where he stood was now a giant bird with craning neck and fiery feathers, with strong, lean talons gripping down on the muddy ground. Marco looked down through hooded eyes, to see the merman's eyes turning wide as a saucer and his mouth gaping, completely astonished. Even the end of his tail stood up straight, quaking in either surprise or in preparation to strike.

"What are you?! How could a human turn into… into… " he trailed off, biting his lower lips with sharper row of teeth, "A… devil fruit, you say? Are you talking about the cursed fruit?"

Marco turned back into a human with ease, as he pondered the question. He knew that even between humans, the Devil Fruit were known by different names, and he supposed in a way, they are quite cursed indeed, "That's the one. I ate it a long time ago, and it gave me the power to turn into a Phoenix, the bird you saw earlier,"

"They gave you power?" the merman seems genuinely confused, "I was ever told they killed you instantly. Well, to merfolk, at least,"

Which, in a way, Marco thought made sense. In trade of his power after all, he lost the ability to swim, and he heard of Fishmen - another aquatic race that was much more well known and common - who did as well once they consumed a Devil Fruit. Unlike Fishmen, who can still withstand walking above water, Merfolks supposedly cannot live too long outside of the water, becoming vulnerable, so eating a Devil fruit would probably kill them instead.

Not that he knows; unlike Fishmen, who lived in - relative - harmony with human, no one has ever seen Merfolks in over centuries.

His stomach rumbled again, much louder this time, and Marco groaned, squatting down on the ground. Right, the big fish turns out to be a living merman, and no matter how hungry he was, there is no way he's going to eat something that looked like him, even only from the top half. At least the water seems safe enough to drink, but quenching his thirst is not quite enough.

"Hey, um, are you alright?"

Though half-lidded eyes, Marco looked up to see the merman again, who had slithered closer and now had a frown marring his face.

Sighing, he nodded, "Yeah, i'm.. i'm just hungry. I was on my way someplace else before the storm hits and brought me here, and before that, i hadn't eaten in 3 days,"

The merman let out a small, surprised noise, "That's…," Marco hear him trail off, and without any warning, he slithered back to the current, using his front arms to move and dipped back into the waters with only his fin again showing up. He reemerged a second later, one hand still submerged into the water as he used the other to wipe his hair back and made a leap over to the stream's ledge.

"Here," he said as he tossed over whatever it is that he had caught. Marco raised his hand up in reflex, finding himself holding something wet and slimy, which suddenly began squirming in his hold that he almost dropped it.

It's a fish, Marco discovered, the merman had thrown him a live and squirming fish.

"I saved him up for later, but you seems to need him more than i do,"

Marco looked at the merman, down to the fish and back to the merman, who was looking at him almost expectantly, "Oh, uh, thank you,"

The fish was on the smaller size, hardly bigger than both of his palm, but by just looking at it made his stomach churn, as if reminding him that food is food, regardless the size and state of rawness. Briefly, Marco thought that his brother would've disapproved of this line of thinking, perhaps insisted in taking it away from him and making him wait until he can come up with some recipe or another.

Marco smiled bitterly, as he opened his mouth and get ready to take the first mouthful bite out of the slimy and squirming fish.

"Hey!" a sudden splash halted and startled him, when the fish was suddenly taken away from his hand, "What are you doing?! You humans really are barbaric!"

In confusion, Marco could only blink, finding the bewildered merman looking at him with disbelieving eyes while gripping on to the fish, "Huh?"

"You were just going to eat him like that? You're not going to put him out of his misery first? That's so cruel! Even after he's okay with you eating him!"

Did he actually hit something while landing here or did his hunger affected his brain's function? Because he cannot understand a word that the merman was saying, "I… uh," he glanced from the still enraged merman to the fish, its (his?) gills puffing open and close repeatedly and the mouth twitching every so often, "I'm sorry?"

"You damn right, you should be. Fishes are okay with being eaten because that's their role in the ecosystem, so you have to show them respect for giving you sustenance in cost of their lives. Ugh, you—" the merman suddenly paused, turning to the fish in his hand with a concerned frown, "Oh, really?" he mumbled, and Marco must be going crazy, because it looked like he's talking to the damn thing, "Then why did he— Huh, well, if you're sure, i guess,"

When the merman looked at him again, he still held some semblance of doubt, but eventually he offered the fish back, "He said human usually do kill them first before eating, but you're probably just hungry. If you apologize to him and promise to kill him first, he said it's fine for you to eat,"

Marco blinked once, twice, several times.

He heard of 'respecting the nature', but this… certainly is a new level.

His stomach growled again though, urging him to go through with it, "Um, i'm sorry, uh… Mr. Fish?"

The fish's bulging eyes seems to focus on him, and its mouth twitches. Marco must be going insane, but it looked to him like his apology was accepted.

"Good," the merman took the fish away again, bringing it close to his face with a benevolent smile. He looked dazzling that way, without the snarls and the frowns, and Marco once again found himself staring, "Thank you,"

The merman raised the fish above his head, and slammed it down to a rock by the stream's edge with one powerful blow.

"The fuck?!" Marco jumped, because holy shit, he did not expected that. The fish was limp on the merman's hold now, and odd as it is, he actually felt sorry now for the little guy, "You just told me to respect him and all and now you just crushed his head?!"

As if he had done nothing wrong, the merman rolled his eyes, "Duh, it's the quickest and most painless way to end their lives, so they won't have to suffer. You humans really are clueless," he tossed the now dead fish back to Marco, but the man missed catching it, only having aquatic animal flop lifelessly on his lap, "There, his school almost always gets the best algae so you can know for sure that he's healthy and taste good,"

He actually did, raw and all, or maybe it was because Marco was so goddamn hungry.

The zoan user was still in the middle of licking his fingers and picking his teeth for some stray scales when he heard the merman laughed lightly, and found him half submerged back into the water, his top half leaning on the ground and looking at him in amusement, "You know, you're not bad for a human," he mused, smiling slightly, "I was always told that humans are evil, that they'll kill me on first sight and that they're always cruel to merfolks, but so far, you've been pretty nice, notwithstanding trying to eat a fish alive,"

Marco swallowed, feeling the slimy and cold fish meat sliding down his throat and filling him to some degree, "I've never met a merfolk before, so i don't know what to say, but you've fed me so i'll say the same about you,"

The merman suddenly turned glum, his lips downturned as he sighed, "I know. No one's allowed to ever leave the kingdom for hundreds of years now," he scoffed, "I'm not even allowed to leave the castle most of the time,"

Castle? "And by kingdom, you mean Raftel, right?"

The dark haired merman nodded. Then the very next second he suddenly turned alert, "Fuck, i'm not supposed to say that,"

Marco couldn't help it, he smiled, saying reassuringly, "It's not a hard thing to assume. Don't worry, i won't ask or anything,"

He was still stared at with some degree of distrust, but after a while, the sunset coloured merman seems to ease up again, "Right. Well, i guess that's fine. The only humans i'm supposed to be wary around are pirates. Whatever that was,"

Marco nearly bit his finger, and decided to do it anyway to stifle his choking. Shoot. Well, it is understandable why they'd be wary of pirates when the entire goal of being one is to find their kingdom and rob them of their most precious treasure.

The blonde cleared his throat instead, and in reflex pulled his shirt close to cover the very obvious tattoo on his chest. It was probably unnecessary, considering that since the merman doesn't seems to even know what a pirate is, there's very little chance he'll connect his tattoo to one of the biggest and strongest pirate crew in the seas, but Marco's can't help but to be self-conscious either way. He doesn't really want to make this merman distrust him.

"So why are you here then, if Merfolks are not allowed to leave their kingdom? I'm assuming it's nowhere nearby?"

The merman turned sheepish for a while, but the line of his lips turned tight, "I'm chasing after someone, a human pirate, at least that's what he called himself. He stole something really important to our kingdom, something that if it falls to the wrong hand, mean my people will be in danger," behind him, emerging from the water, his tail flicked, the movement stuttered and tense, and his face darkened in anger, "and in that process, he hurt one of my brother,"

The small bite of fish meat fell out between Marco's teeth as he gaped at the merman. That's… that's quite the coincidence.

"Me too," he rasped, biting down the bitterness that began to bloom in his chest, "I'm on a chase for someone. He… he killed one of my brother, and stole something dangerous. I have to stop him before he can cause any further destruction and as a payback,"

A plopping sound from the stream marked the merman's tail curling back down to the waters, the fin gently floating along the surface as he gazed at Marco with pitiful eyes, "I'm… i'm sorry to hear that. My brother was hurt, but he's still alive. I can't imagine what i'll feel like if i lose him,"

Marco could only smile, halfhearted as it is, "Thank you,"

On the overhead, the sky began to darken, splotches of red decorating the previously bright blue. It's getting late, Marco thought, and he should really be on his way.

Still, where exactly is he?

"I don't suppose you can tell me which direction to take, can you? I should leave soon, but it's too dangerous to go without any set direction,"

The merman perked up, "Oh, right, you can fly unlike other humans," he hummed, staring to the distance where the stream leads, most likely to the seas, "Well, it's a little tricky. No human were ever supposed to come close to this place, but since you said you've been brought by a storm, it kind of made sense. You probably couldn't have found this area on your own,"

Sounds like this place was much further away from where he had been originally. Shit, he's been wasting precious time then. Who knows if his target was still where he is.

"Okay, you look nice and trustworthy enough, and it is also my duty to chase away any unwanted guest," the merman spoke again, a hint of smile on his face, looking much more friendly than he had been just a while ago, "Well, usually that means killing and drowning you, but you're not a pirate and you only got here by accident, so it won't be fair if i did,"

Marco swallowed, "Y-yeah,"

At least his nervousness went undetected, because the merman only smiled, "I'll tell you what, i have to go on with my journey too anyway, so i'll lead you the way back to the human waters. It's not too far, and from there, you can go on your way again and get revenge on the man who killed your brother,"

There's a clench in his chest after hearing that sentence, but Marco nodded resolutely, "Right, and you need to find the one who hurt yours and stole your kingdom's treasure,"

"Exactly," the merman nodded with an equal amount of conviction, "Oh, by the way, my name's Ace. Humans also have names, right?"

Ace, what a nice and very fitting name.

"We do. I'm Marco,"

"Marco," Ace said slowly, as if testing his name and damn, it sounded nice to hear his name from that voice, "Alright then, Marco. What do you say we make our way out of here?"

* * *

Ace's tail design was inspired by Siamese Fighting Fish because one, they're beautiful, and two, i have one at home, and three, appropriate to their name, they fight everything and i don't think any other combination can suitably match best boy better.

Thanks for reading and hope you liked it! Please tell me what you think!


	2. Chapter 2

Yes, i am continuing this. I'm so sorry and thank you for staying and tuning in.

Just before we started though, the way this fic developed seems to have some spoilers…. at least to those who hadn't catch up to Fishman island. Which ended like… what, 5-6 year ago manga wise? And please note while there are still some elements of this story that will follow the manga (specifically how merfolks works) there will be some… major changes, like some characters not existing, how things works, etc. I mean, it is an AU, just that it took the same universe as the canon because i'm not very creative.

Anyway, please enjoy the butchering of the canon plot to fit this entire fic and i hope you'd enjoy!

* * *

If there was ever any doubt he was in some sort of other world, then all of it disappear the minute he took to airborne.

Flying above these strange waters had been an experience indeed, when instead of just the great expanse of blue underneath him, Marco could see rainbow like gradients blanketing the entire ocean top, which later on he found to be schools of fishes and, much to his surprise and consternation, the occasional sea kings swimming along by Ace's side, thankfully in a docile and benevolent manner. The waters almost had no ripples, disturbed only by these movement, and even the breeze felt different up in the air, denser and forcing him to fly lower than he usually would.

Before they started this journey, Ace made a point that he'd be swimming closer to the surface so Marco could follow him from above, and since their first mile, Marco couldn't look away from him for a different reason. Amongst the colourful water surface, reflecting the bright sunlight above, Ace's fins, both at the end of his tail and by his waist looked almost ethereal, fanning wide and in such an elegant motion it was as if he himself was some sort of a aquatic avian. His tail sways expertly and fluidly, the darker colours emphasised even more by the shimmers of the water, and the light blending in almost like a camouflage.

Likewise, however, he had the feeling Ace was intrigued by him, if the way he would sometimes glanced up for a while wordlessly seems to be of any indication.

Right now, they're supposedly about halfway to 'The Gate', as Ace had called it, and going by the speed they had, they should arrive tomorrow before the sun sets. He had wanted to push on, but decided not to risk it again, and they both ended up landing in a small coral islet - though considering that just by sitting allows him to see one end to another, he'd call this more of a 'rock' - to rest for the day.

He hadn't even landed properly on the gravely surface when another odd wonder happened; the same school of fish, closely resembling trouts, that had appeared and swam along with Ace pooled by the shores and surrounding the young merman. With curiousity, Marco watched him seemingly communicating with them - which apparently what he was doing - before plucking one of the calmly swimming fishes out of the waters and turning to the half transformed zoan, "Dinner?"

Marco blinked, looked down to the waters and nearly jumped out of his skin because in an almost trained move, all of the fishes turned towards him, their big, round eyes staring unblinkingly. There has never been a more unsettling display that he ever come across in his life.

"Do they, do they follow you around to," the blonde gulped, trying to calm his racing heart down and only focusing on looking at Ace instead of the unnerving fish eyes from under the waters, "to offer themselves as food?"

Ace looked sheepish, "Well, um," he mumbled lowly, lowering the fish in his hand down to his lap - or whatever a merfolk's equivalent of a 'lap' was, "I guess… in a way?"

The fish in his hand squirmed out of his hand but stays on his lap, flopping a little to bounce over colourful tail.

Closing his eyes and taking a deep breath, Marco decided he's not only in different waters, he's in a different world altogether right now, a world where apparently, your food comes to you willingly. If he thought about it that way, it seems more pleasant and less aneurysm inducing.

Besides, he is feeling a little peckish after flying all day.

"Okay, sure, dinner it is,"

* * *

"So what's Raftel like?"

At his question, immediately, Ace stopped humming - which is too bad, because whatever Merfolk song that was, it sounded quite nice - and regarded him with a look of suspicion, "You don't have to tell me about where it is or anything," Marco quickly added, before the merman can say anything, "I was just… curious. Even the seas here seems so different than the ones on, uh, on human seas,"

Yeah, for one, the fishes doesn't actually form a queue waiting for you to eat them. After the initial school that follows them were diminished to nothing - Ace eats a hell lot, and he's scared for the population of fishes everywhere to know if that's a Merfolk trait or an Ace trait - another suddenly appeared, this time much longer and larger than the last ones and bore close resemblance to pike fish.

At this point, Marco was full and honestly tired of saying 'thank you' and feeling conscious about every other fish he was about to eat, so he simply sat back on the edge of the rock and watched Ace in the waters underneath tore into the last of those pike-like fishes, sharp incisors ripping through skin, meat and bones alike. Which was both fascinating and rather terrifying at the same time.

Hence, the attempt to start a conversation.

Ace was still watching him through narrowed eyes, but eventually lowered the half eaten fish down and gazed to his side, "Well, Raftel's one big kingdom," he started, "It spans hundreds and hundreds of miles, and in the centre of it was Castle Oro Jackson, where the royal family lives,"

"Like the king, queen, prince and princesses?" Guess even that sort of hierarchy stays even within the Merfolk society. Marco snorted derisively, wondering if there is also an equivalent of the World Nobles behind that and hoped for the sake of this seemingly peaceful seas that there isn't.

"King, queen, and…and a prince," at the mention of the prince, Ace's face furrowed, his lips thinning almost in dislike.

Which Marco noticed and found intriguing, "You don't like them?"

The merman shook his head, damp hair swaying gently with the motion, "No, everyone loves the king and queen. King Roger's kind of silly at times, but he's a good ruler and the strongest amongst all Merfolk," a small smile made it to his lips then, as he took another bite and swallowed after barely chewing, "Queen Rouge is the kindest mermaid you'd ever meet. Mo— The queen's often spend time exploring Raftel, talking to the citizen and she knew basically everyone by name,"

He sounded genuine enough, but Marco noticed he missed one, "And the prince?"

At this, Ace's face grew sullen, "The prince is sheltered. He always has to have guards with him, he can't leave the castle most of the time, because 'the outside world is dangerous'," he sighed, taking a rather impressive bite out of the fish in his hand and within two bites, finally finishing it. Marco looked away briefly, horrified and slightly sickened, "All he wanted was just to explore, to see new things in life. There's got to be more beyond the gold plated walls of Oro Jackson, beyond the tall walls of Raftel, even… even beyond The Gates,"

His melancholic tone, coupled by how he said his last sentence made it sound like he was talking about himself instead of someone else, something that piqued Marco's curiousity and suspicion.

One of the pike fish, from what few who was still left, swam closer by Ace, seemingly nipping and butting its head against his tail. It almost looked like it was trying to comfort him, and to prove Marco's guess, Ace placed one hand on top of the fish, caressing over its impressive length. Kind of weird that the fish was still willing enough to do that after watching its brethren consumed in an amazing speed by the same merman, but what does he know about the dynamics of fishes and Merfolks?

"Now's my turn to ask," with a splash, suddenly Ace was facing him, leaning his upper body against the edge of the rock while his tail sways calmly on the water to keep him afloat, "What's the human waters like?"

"Uh," was all Marco could say while faced with the sudden enthusiastic interest, "What do you want to know?"

"Everything," the freckled merman grinned freely, before he suddenly turned rather serious, "I also need to know what to expect on my travels to take back what the human pirate stole. I only ever heard bits and pieces about human waters from old Crocus, but everything that he told me came from a time when he was still much younger, so his story is always so confusing and it's probably a lot different now out there,"

He then paused, and mumbled lowly, low enough that Marco could barely hear him, "Well, before Mom and Dad forbade him from telling me more, anyway,"

It never really occurred to Marco till then, but, "Wait, are you telling me you're planning to chase for someone out in a world you have never seen or have been to, didn't know anything about, and probably also without direction? That's… that's really thoughtless of you. Thoughtless and reckless,"

A deep flush quickly made their way to Ace's face, turning the serious gaze to become flustered, as the young merman started blustering, "W-who are you calling thoughtless and reckless?! That's why i'm asking you now, aren't i?! And i'm not really without direction! I know exactly where to find that human pirate, i just don't know anything about the place he'd be in!"

"How… how does that work? You can't possibly know where he'd be if you don't know where he'll be," Oh boy, he's getting a headache just saying that.

"Well, i can!" Ace insisted, but instead of explaining, he fell quiet, cheeks puffed up slightly still in anger and indignance.

Marco looked at him rather warily, "…How?"

The young merman pressed his lips together, almost looking like he was briefly contemplating something. He seems to finally reach a decision when took a deep breath and finally spoke, "I know because what the human pirate took is a precious artefact, and merfolk royal families resonate with them, allowing us to know their location at all time," his cheeks turned even deeper red after he finished saying that, eyes darting away from Marco and his face the epitome of reluctance, as if he had shared something he hadn't wanted to in the first place.

And that's when Marco realized, and had the sudden need to lay down for the nth time since he first arrived in this strange areas.

That explains his rather personal description earlier.

"W-what now? Why are you sighing like that?!"

"I'm just too old to get so many big surprises in such a short time, is all," Marco answered flatly, "So let me get this straight, you're the merfolk prince, " Ace's face flushed again, and he would've called it adorable if his head wasn't pounding from the inside, "and right now there's a pirate somewhere out there who managed to not only find Raftel, but managed to steal… what, One Piece?" Oh great, so while he's here, away from his own 'waters', someone out there aside from Pops is already the King of Pirates, and probably the world knows already.

Suddenly his dinner doesn't settle well in his stomach, and it's not because he had eaten them raw.

"No, no other human than you had came close to this place, much less Raftel," Ace told him with a shake of his head, frowning, "And no dirty pirates ever came close to One Piece, we'd drown them first before they can. But the artefact they stole was no less important than our kingdom's greatest treasure,"

Well, that's one relief, he suppose, "How'd they steal it if they never even found Raftel?"

"Because Poseidon, the artefact, is not kept in Raftel," Ace bit his lower lips, his tail underwater swiping away and making a big splash left and right, "I don't really know why either, i don't even know what Poseidon is or what it looks like—"

"Oh boy," Marco moaned in despair.

"Will you let me finish!" the merman barred his sharp row of teeth almost threateningly, "Poseidon is kept in a different location, somewhere in the human waters, in a place only scholars and guardians of the artefact can access," with a pained voice, he looked down to his folded arms, fringes falling and covering part of his face, "My sworn brother is one of those guardians. He was accompanying the general on their way for a routine check when these… these human pirates attacked, somehow finding out about the location,"

Ace was upset by this turn in the conversation, that was clear, so Marco pushed away his disbelief over how completely unplanned and spontaneous the merman's journey was and offered, "I'm sorry,"

It earned him a small, genuine smile from the sunset coloured merman, "Sabo's alright now, at least, he seems so before i left. He told me that he himself also never got to see Poseidon and only Dragon, the general was allowed to. That's why i don't know about it, most of the things i gathered before i left were stories from him," he pursed his lips, brows furrowed before continuing, "The other thing that i was told was about the human pirate,"

"What was he like?"

"Dark, curly hair, fat, missing some teeth," Ace said with disdain, and Marco wanted to tell him that plenty of pirates he came across in his life looked like that - hell, he can name at least 5 people who fit that description on board of Moby Dick - when the dark haired male continued and he felt his blood run cold, "And he had this strange power, like he could control darkness itself,"

"Teach,"

"Teach you what?"

"No, Teach. You're describing Marshall Teach, the man that i'm after," he felt like all breath was knocked out of him, head spinning due to confusion and sudden, flaring rage, "The son of a bitch who killed Thatch,"

Ace's dark eyes widened in shock, his tail growing limp as they both stared at each other wordlessly.

What are the odds, truly, what are the odds.

* * *

The Gate, as it turns out, is a large formation of mountains. Which seems surprisingly underwhelming until what happened next.

As soon as they arrived, the rock-like formation actually _moved,_ showing that it was in fact a very large, flaming red sea king emerged from the depths of the sea, its two jutting lower teeth bigger than 3 of Marco's Phoenix form and its long neck. It looked angry, glaring down with its stern eyes at the two of them. A single exhale from the creature blows strong wind against them, disturbing the water surface and almost blowing Marco away from the sheer force.

But as concerned as Marco was of this sudden appearance, Ace looked otherwise, poking out of the waters and lifting both of his hand while cheerfully calling, "Oars Jr.! It's me!"

And Marco knew he's in for a 3rd day full of surprises, because the sea king let out a keening sound as it lowered its head down to the waters, submerging down to his jaw to carefully _sniff_ around the young prince.

Sea kings being docile. He had seen everything there is to see.

Ace laughed, patting the humongous snout poking at him, "Hey, buddy, long time no see!" the sea king cooed, eyes closed and almost looked pleased at the way Ace's hands petted his scales. There's something really odd, seeing what was probably the largest sea king he had ever seen in his life acting like a common puppy to a creature thousand times smaller than itself, because that is exactly what this is. Ace is treating the sea king like a normal, every day domesticated animal, "Aww, guarding this place must be really boring and lonely, huh? Sorry, i wish i can sneak out more often to meet and play with you,"

The sea king, Oars Jr. let out another sad little noise, the sort of noise you won't expect a creature that big to make. It then let out another noise before rolling his slitted eyes upwards, to where Marco was.

"He's a friend, Oars Jr.," the young merman said, "And we both need your help right now. We want to go to the human waters,"

Head bigger than a mountain turned to the merman before the sea king let out a roar, the sound alone disturbing the waters and pushing Marco back yet again, "Please, Oars Jr., you have to help us cross the gate. You know what happened to Sabo and about that human pirate," in reply, the sea king let out a quieter roar, and Ace's expression turned hard and indignant, "Dad can take me back kicking and screaming, i need to do this,"

The sea king turned quiet, letting rumbling noises from its throat.

"Please,"

With one last whine, the large sea king lowered its head again before it opened its mouth, and with a single glimpse, Marco can already guess one of the reason why even if anyone managed to find this place, no one would live to tell the tale. There's three row of teeth inside of the creature's mouth teeth and jaw could unhinged large enough to destroy Pops, Big Mom's and Kaido's _entire fleet_ combined. Even the toughest pirates will have great difficulty beating this particular sea king.

Ace made his way over to the unhinged maw, holding on to the tip of one tooth before he turned around to Marco, "Hop on in,"

Marco could not comprehend.

The merman frowned and, using the same tooth he had been holding on to as a support, leaped _into the sea king's opened mouth_ , "Marco, come on, hop right in,"

The bird blinked hard, looking away from Ace to the enormous pair of eyes looking at him patiently.

"Oars won't attack anyone who is not a threat to Raftel," he heard Ace said again, taking his attention back to the young merman to see a rather amused expression on his face, as if he found Marco's cautiousness about randomly jumping into a sea king's mouth funny, "Hitching a ride with Oars Jr. is the quickest and safest way to get to your waters, so come on. We promised to help each other out in our hunt for this Marshall Teach, right?"

Ace extended one webbed hand, smiling, and Marco relented.

 _Thatch,_ the zoan called out mournfully before he warily flew inside of the sea king's mouth, and the large cavern close down around him, _looks like i'll be going to wherever you are soon instead of avenging you._

* * *

Ya know, after i finished writing out the outline and finished with this chapter, i realized something: Throughout the fic, if you know what was different, and at the same time similar about how things work in this fic and the canon, you can probably already guess how this fic is going to go.

…Which is something i probably shouldn't have said but hey, keep it to yourself if you figured it out *finger guns*

Thanks for reading, please tell me what you think and hope you liked it!


	3. Chapter 3

Warning: Gore. See the not-so-nice side of an angry merfolk.

Hope you'd enjoy!

* * *

"Bye Oars! Thanks for the ride!"

The vermillion sea king let out a loud, echoing noise that sounded almost mournful, as if it was trying to say how reluctant it was to leave. Yet it slowly sunk back down to the waters, creating a giant splash before it disappear to the ocean depths.

Ace turned a few steps away from the shores where he lay, rolling his eyes at the hunkered and gasping form, "Oh, don't be so dramatic, so it was a bumpy ride, but we're here now,"

"I thought i was going to die,", Marco sputtered, laying down on his front before rolling to his side on sweet, sweet, unmoving ground.

It felt like he was caged bird being jostled about, only instead of a cramped space and uncomfortable metals digging to his feathers, it was wet and damp everywhere. He was sure he knocked his head on Oars' extremely hard teeth a couple of times, but at least gagging over the smell of sea king breath brought his mind off the worry over the rushing sound of waves outside and the fear that Oars will open its mouth and forgot that one of its passengers do not have the ability to swim. Or can swim at all.

The reason why they had to 'hitch a ride', as Ace told him during those worrying moments of being inside a sea king's mouth, was because their two waters were separated by an incredibly strong current that could only be ventured around by a creature as big as sea kings. Centuries ago, before the merfolk sealed themselves from existence, there was a pathway to bypass those currents, but it was sealed to ensure Raftel could not be discovered, and could only be opened by unknown methods.

The very same methods pirates all around the world sought after, along with the location of the waters itself.

When his heart and nerves finally calmed down, Marco stood up, shaking his head and ignoring the smell of sea king saliva clinging on to his clothes to look around. He still didn't recognize where he is right now, or can tell if he is really back, "Where are we then?"

Ace shrugged, "I know we're in your waters now," he said, curiously looking down to the sand underneath his hand and faintly flipping his tail behind him almost experimentally, "It doesn't look all that different from back home, but at the same time, it does. The waters felt different, a bit colder, smells different too," his lower lips jutted out a little, and if Marco didn't know any better, he'd say that Ace was actually disappointed about this.

Oars seemed to have placed them on an uninhabited island of sorts, which is both a bad thing and a good thing. The good thing is, there won't be people freaking out over seeing a sea king emerging out of nowhere to spit out a human and a merman out of his mouth. The bad news is, there is no one to ask about where he is right now and with him losing all of his stuff and his log pose, there is no way Marco can find out.

Still, there's only one direction that matters to them now, "You said you know where the artefact Teach stole was, right?"

At the reminder, Ace turned solemn, his wide curious gaze turning narrow and concentrated. Slowly, he gaze to the distance, to a direction in the wide blue expanse, "I can feel where Poseidon is, yes," he muttered, his tail growing tense and making a small wave on the shores, "It's… it's far away from here, somewhere in that direction. Unmoving,"

Marco was genuinely curious as to how 'feeling an artefact' worked, but there are more pressing matters to attend to, "If it's unmoving then that means Teach is probably laying low instead of sailing away. Do you know how far it is?"

To his displeasure, Ace shook his head, seemingly equally regretful, "It's fine, but we better get moving now," with a swirl of blue flame, Marco's limbs turned into fiery feathers and long talons, ready to take off, "We won't know until when Teach will stay in one place,"

Ace nodded, his face serious, but his tail wagged rapidly and Marco can't help but to think that he's also a little bit excited inside.

* * *

It wasn't until a couple of hours of flying did Marco got a solid confirmation that they are back on 'his waters', when he spotted the first pirate ship he had seen since his return.

Their jolly roger was nothing familiar, which means they're not friend or foe, and they are also not quite well known. The ship was small and brand new, and as he flew past them, there were only about 3 people on the deck milling about, with another one he spotted by the bird nest.

That one raised up his binoculars and whistled, before shouting quite loudly, "That's a big ass bird. Does Grand Line make birds that big?"

In hilarity, he crooned an aviary laugh. It was nothing new, and, as is always the case with new pirates, they would have little to no idea of what he is, so they'd let him fly pass, probably thinking he was just some Grand Line wonder. Still, it was always amusing to hear people commenting on his passing by, and sometimes, when he was in a playful mood without an urgency back on the ship, he'd fly lower by their ship or even perched by their railing, just to confuse them a little.

Sometimes, a few kindhearted young pirates fed him bits and pieces, which was always a plus, and the few occasion when someone ended up recognizing him from the mark on his chest, and usually, their reaction made it all the better.

Sadly, he is in a very strict time constraint, so he glided above the ship without a word, eyeing the waters to see where Ace had gone to.

Only, he couldn't find him.

A moment of concern was amped up even more when there was shouting from down below, and he quickly whipped his neck to the direction of the pirate ship from earlier, where the terrified scream came from. He quickly dove down in urgency, his instinct flaring and telling him that Ace's sudden disappearance and the scream must be related.

The three men on the deck was now reduced to two who were frantically searching the waters, with another one emerging from inside of the hull, "What happened?!" the newcomer, dressed in a fashion and with a hat that told him this might be the captain asked the crew members, while the man on top of the bird nest hastily climbed down the sails and almost tripped a couple of times in his urgency, "Who screamed?! What's the emergency?"

"Something jumped out of the water and took Phileas!" one of the men screamed horrifically, "It… it looked like a giant fish and it was.. it was orange, and red and… oh shit, it's back!"

Marco snapped his attention to where the man pointed to in panic, to catch the exact moment a blur the colour of fire indeed jumped out of the waters on the deck, right behind the other unfortunate pirate leaning down the railings. The man screamed in fright, his balance already off due to his earlier position, and he barely put up a struggle with his flailing arms when Marco caught Ace's claws diggings to the sides of his head to pull him into the waters and instantly disappears into the deep blue.

"Kenway!"

"What the fuck was that?! That's no fish!"

The captain fumbled with the gun on his side, inserting a bullet into the chamber with a shaky hand, "S-shit, shit! I'm not dying just after reaching Grand Line! Take out your swords and get away from the railings!"

In haste, the last two remaining crew member did as ordered, hurrying by their captain's side.

Only, one of them, the one Marco remembered had been on the bird's nest hadn't even take more than 2 steps when a loud splash was heard again along with a feral cry, and suddenly, Ace landed on to the deck, sharp, lethal teeth not unlike those of the wildest predators bared menacingly and his claws digging deep into the ship's floor. With a hiss, he clawed deeper into the floors, the wooden materials easily giving in and forming three deep, lined indents as he pounced.

In fascination, still airborne, Marco watched Ace's claws pierce into human flesh even easier than it did the wooden floors. The man howled, eyes squeezed shut so tightly tears made their way out of the sides of his eyes. They both fell, with Marco and the two other on the ship only watching out of shock, as Ace dragged his captive to the edge once more, slowed down only by how much the man kept screaming and struggling.

Out of the corner of Marco's eyes, he saw a glint, caught the captain raising his gun shakily as he whimpered, "A-a-a-a… A m-m-me-mer-merman,"

On the trigger, just as shaky as the man, his finger slowly pressing down.

Without thinking, Marco dived for him, snatching the revolver out of the pirate captain's hand and taking him down along with it. There's a sharp cry of surprise from the captain, and he tried to yank his arm away from Marco's talons to no avail, and in his struggle, the revolver fell off from his grip, sliding away on the floor and out of his reach.

The firearm was quickly picked up by the last member of the ship with his shaky hands, who distanced himself and aimed unsteadily between the zoan on top of his captain and the merman and his bleeding out friend who almost reached the edges, "The fuck—where'd all these creatures came from—" he cried out and that was all that brought Marco's attention to him and the revolver in his hand, just as he settled his quivering aim towards Ace's direction.

The zoan screeched, making the man jump and thankfully missing his shot by a mile. The resounding bang captured Ace's attention, who seems perplexed by the sudden loud noise.

For a split second, nobody moved and made a sound. Then, as if in slow motion, Marco caught the change in Ace's expression; the blank expression slowly morphed to something ugly and vicious, bloodied teeth barred, his fins seems to fan out threateningly, spiking out like an angry hedgehog, and the darkness of his pupils expanding as a spine-tingling shriek was released from within. It was something inhumane and otherworldly, chilling even to his core.

That shriek echoes through the empty air, slowly dissipating to nothing until he caught it; the sound of rumbling and the disturbed waves. Every instinct built in both as a phoenix and as a human blared inside of Marco's head, telling him that something is definitely wrong, that something dangerous is approaching fast. The pirates were still distracted, paralyzed by what they had just witnessed in such a short span of time, so he was sure he was the only one who saw the dark shadows slowly coming into existence from the sea.

In a torrent of sea water and with a fanfare of loud bellows, comes out a sea king followed by another, and another, each of them towering over the small, disturbed ship only as big as their large, bulging eyes.

With a mighty roar, the one on the front, a mollusk-shaped sea king snapped one of the antennae shooting out of its head to the ship's surface, and right before his eyes, Marco watched the terrified pirate holding the gun crushed underneath the heavy weight, not even having the time to scream. When the antennae was lifted once more, there was nothing but splattered human remains on the floor, connected to the rest of them still attached to the grimy and slimy surface of the sea king's limb with a sickening string of tissue.

In his disgust and stupor, Marco narrowly missed the approaching long necked amphibian sea king, whose hiss was the only warning that succeeded in making him dodge the incoming shadow and narrowly flew out of range. The captain, the sea king's prime target as he come to find out, was not so lucky, his body trapped and penetrated by series of sharp tooth that devoured his entirety before he can even finish saying, "No, please!"

From between the sea king's mouth, the man's hat slowly floated down back to the deck, ownerless.

Another shrill scream brought his attention back to the deck, where he saw Ace and the now bled out man limp on his hold, and the third sea king, stocky in build and with outer skin rough like a rock floated slowly towards the ship, looking much calmer than the other two, who has now distanced themselves away yet still patiently waiting. Once it was close enough to the ship, it opened it's mouth right on the top of its head, shaped like eerily deep the open top of a volcano.

With little effort, Ace tossed the body he held into said cavern, which closed down once again like a shifting rock. The sea king let out a little humming noise, ringing into Marco's ear like some sort of a pulse, slowly surfacing from the water to lean down close enough to the sunset coloured merman. It hummed again when Ace placed a gentle hand to its side, running through the rough texture and giving it a small pat, and with that, it sank back down into water, the other two now long gone.

Suddenly, there's only the two of them left, Ace still on the edge of the ship and Marco now landing on the deck, arms still in the form of wings but he couldn't concentrate enough to change them back fully. Too much passed by his mind, too much to fully understand, so all he could rasped out was, "Why?"

Casually, with his eyes blank and head tilted, the entire look of genuine and innocent confusion by his question was ruined by the blood still dropping out of the corners of Ace's mouth, the same as the grime still sticking to his hands, "What do you mean?"

"Why'd you attack them?" the zoan barely realized his voice was slowly raising, that his eyes had gone even wider, "Why'd you— why'd you kill them?"

At this, Ace's eyes narrowed down, baffled, as if he can't understand why he is being asked for slaughtering an entire ship, "Don't you see the that drawing up there?" he lifted a hand and pointed towards the lone jolly roger on top of the sails, and due to this motion, a single drip of blood traced down in a twisted line from one of his fingers to his forearms, "A skull and two crossed bones. They're human pirates, the ones we're hunting down,"

It was said in such a casual tone that Marco knew he didn't see anything wrong with what just transpired, didn't see the problem that, "Ace, these people has nothing to do with Teach. Their not even from the same crew, probably never even came across each other,"

Again, Ace furrowed his brows, "Why does it matter? They're still pirates, they still need to be rid off,"

"Wha— No!" The merman was taken back by his outburst, but Marco's face felt hot and as was his head, feeling slow bubbling anger inside of his chests, "They're still people! Innocent people! They hadn't done anything!"

"Innocent?! They're human pirates! Pirates are the ones who hurts Sabo and they deserve it!"

"No, _Teach_ was the one who hurts your brother! These people has nothing to do with it! They don't deserve to die just because!"

"W-why are you defending them? Humans also hated pirates, don't they? Crocus said they're so evil even their own kind hates them!"

Marco was silenced, not because he was out of word, but at the reminder of the origin for Ace's perception of pirates. Hearsay and stories by merfolk who probably doesn't even remember what life was like in these areas, to pirates, who might as well be their entire kingdom's natural enemy. It gave a bitter taste into his mouth, reminding him as well of what he was still hiding from the young merman, of why those words hits too close to home and why all of the deaths just now was so unacceptable.

"Maybe," he answered shortly, gathering his breath, "Some of them are, like Teach. But not all of them. What you just did wasn't only unjustified, it's just senseless killing,"

"And why is that wrong?! They're evil!"

"Because it's a waste of life, Ace!" there's a crack underneath his foot as he stomped, creating a hole on the floor due to the _haki_ he unconsciously channeled in his frustration. Ace's tail snapped up straight as the young merman let out a surprised gasp, eyes wide at the sight of the indent left by his _haki_ -imbued feet, "You called us humans barbaric? Look around you and look at what you've done! What makes you think all of this carnage you caused made you any different from these so called pirates?!"

Ace fell silent, though his face clearly showed defiance. Exasperated, Marco shook his head, to the smatter of human remains just a few feet away, and lastly, to a lone hat with a jolly roger stitched to the right in the middle. He picked the hat up, dusting it off to take a peek into the inner rim. Aside from a couple strand of human hair, he found the name 'Ahab' stitched onto the back of it, in an asymmetrical yet tidy work that told him it wasn't done professionally but rather handmade, probably from someone close to the man.

Marco exhaled, swallowing down the bitter taste that suddenly rose to his taste buds, before glancing to the door leading deeper into the ship. It felt wrong to even consider this after what he had just said, but no sense in just leaving everything the crew might have behind out of guilt, especially when he realized they're in dire need of supplies for a trip who knows how long, "Stay here," he told Ace without even turning to the merman, walking to the direction of the ajar door, "I'll see if they have anything we can take with us,"

The ship was indeed as small as it looked on the outside, with only a room making up the kitchen, workshop, and probably even communal. A pot was boiling on the small singular stove, letting out a savoury but rathe burnt smell. Marco quickly made his way over to turn it off, taking a peek inside of the pot to see that today's lunch was supposed to be stew of sorts.

Both the sight of cooking food and the hat in his clutch made his chest twisted something terrible. No one would've died today, if not for a vindictive merman who can't just swim by. Thatch hadn't need to die a month ago, if Teach hadn't been an ambitious and sick son of a bitch searching for power.

Taking in a shaky breath, Marco placed the lid back on to the pot and made his way to the pantry.

There weren't much food left but there's enough non-perishables for a couple of days. By the area that seems to be reserved for lounging and games, if the cards strewn around was anything to go by, there's a couple of weapons stashed. Marco didn't really need any of them, but he still take along with him a small dagger, lighter than the one he lost during the storm and in a poorer quality, but it will have to make do for emergencies.

A second room adjoined to the first was obviously the barracks, with a couple of hammocks tied to poles and only one proper bed on the very corner of it, most likely the captain's. He found a couple of clothes that could fit him, a little tight around the chest and waist but a decent replacement. He tried not to rummage too much into the pirates personal belonging, believing there is still some sort of boundary that he needs to set even though they won't be needing any of this anymore.

On the section of the room that belongs to the captain, he found a rather hefty bag of bellis and, to his relief, a working log pose. The blonde gathered everything he found into an old but mint leather sling bag he found on one of the pirate's trunks, and as he gathered the log pose, he found a picture frame right behind it, with an old picture of the pirate captain grinning in the middle of two equally happy little girls and a gracefully smiling young woman clinging to his arms.

Marco closed his eyes, muttering under his breath as he put the hat right next to the frame, and left without looking back.

"Ace," he called out as he stepped out from behind the door, walking back on to the deck, "I found a working log pose in there and some amount of belli. We can go— Ace!"

On the floor, right in the middle of the deck, lying unmoving and unresponsive to his shouts was Ace, lips slightly parted that gave out weak, tiny gasps, which Marco could only hear once he got close enough to gather the merman into his arms, with one arm behind the naked toned shoulders and his other trying to turn Ace's face to his direction, 'Ace! What happened?" There was no answer, but Marco noticed the skin under his hand skin was rough and dry, nothing like how silky and wet it had been the last time he came into contact with the merman. His face was pale beneath the curtain of dark hair that sways along with the weak rolling motion of his head.

When he opened his eyes, Marco noticed that they looked foggy and unfocused, even slightly red on the corners, "—breathe..,"

"What? What do you need? Come on, Ace, tell me what's wrong,"

The merman's dry lips opened a fraction wider, making a barely there whisper, "I can't… breathe,"

Breathe?

The revelation came slamming into Marco's head. Of course, Ace is half fish. Fishes can't live that long on dry land.

Tightening his hold on the slightly smaller male, Marco lifted him up, but only managed to raise Ace a couple of inches above ground when he found that his tail, even dry, was extremely slippery and, more importantly, boneless. After a couple more frustrated attempt, he finally gathered Ace by having them chest to chest, with both of the merman's arms on either side of his neck and his head limply on his shoulder, as Marco used his forearms to support the less slippery part of Ace's tail that was close to his human waist. Awkwardly, he rushed over to the edge of the ship, trying not to trip on the long tail or the sweeping fins along the way.

"D-do i just— Do i just, toss you back to water?"

He felt weak nodding on his shoulder, and with a heave, he did so, wincing when Ace's body made a rather painful smacking noise as it hits the waters and became submerged, "You okay?"

No response, and for a moment, the zoan worries that he had made a grave error when Ace suddenly reemerged to the surface with a long gasp, completely drenched and regaining colours back on to his skin.

Marco let out the breath he didn't know he had been holding in, knocking his forehead to the forearms resting on the railings and huffing, "Seriously?"

"I didn't know it would feel that bad, or it would happen so quickly," Ace said indignantly, puffing his freckled cheeks, "I've never been allowed to spend such a long time outside of the waters before,"

The blonde zoan stared at him for a while, before nodding, "Ah, right, the sheltered prince,"

Obviously, the reminder of his status caused annoyance to the young merman, who let out a small 'grr' sound while glaring at him. Marco ignored it by rolling his eyes, "Come on, we best get going. We've wasted too much time here,"

* * *

Poseidon - and along with it, Teach - was still far ahead, and as the night began to fall, they found a small island to rest, complete with a stream that Ace can enter from and rest more comfortably in rather than on a beach shore like he had the day before. Marco quickly discovered that even the fishes in these waters has the propensity to offer themselves to offer themselves as food to the nearest merfolk, but this time, instead of eating them along with Ace, he settled for the canned food he had taken from the ship earlier. He might be a bird zoan, but his stomach can only, well, stomach so much raw fish and his human side can only tolerate these eager-to-be-eaten fishes even less.

"Why didn't you go back to the waters as soon as you felt faint, anyway?"

He expected some other flimsy answer, so he was rather caught off guard when Ace's face turned sombre, though he quickly hid it by bowing his head down and making his fringes fell in front of his face. The swarm of fish by his side quickly swam closer, rubbing and nudging at him in a gesture that Marco was sure now supposed to be comforting, "Some fishes appear nearby the ships after you went inside," he said, voice soft, "They say the human pirates were a cheerful bunch, and often fed them scraps,"

He felt guilty, was what Marco can easily surmise from Ace's tone and words, and he could remember that he had found Ace in the middle of the deck, near the pirate's gory remains instead of near the railings, where he had been before Marco left him to his own devices.

Sighing, Marco placed his canned food down, "I get that you're wary of them,' he said patiently, giving the merman a wry smile when he slowly lifted his head to meet his gaze, "But aren't you here because of your brother and your kingdom's artefact? Killing just about every pirate you came across is not only foolish, it'll also be dangerous. You don't know how strong they can be, and," And there would be plenty of pirates who won't care about morals, who'd see a merman with their own eyes and will do anything in their power to get their hands on one.

Fuck, he never even considered that, after arriving back here. And not just any merman, but the prince of Raftel himself, in search of a secret artefact currently stolen away from the kingdom. It is possible for them to simply avoid every populated islands until they found Teach, but there is no telling what would happen of Teach ended up being in one. And how would they get this 'Poseidon' back to Raftel anyway?

"And?"

"And we can't attract too much attention to ourselves, or else, Teach will know he's being chased after,"

With pursed lips, Ace nodded slowly, "I still don't trust them, though," he murmured, before going back to eat quietly on the stream.

Marco didn't think he would. Not that easily.

Still, as they continue on with their journey the next day, the next time they came across another pirate ship, with relief, Marco watched as Ace simply dived deeper into the ocean, disappearing out of sight.

* * *

I believe that while they do kill and all, but the likes of Shanks, WB and even Roger wouldn't tolerate just straight up murdering people for no reason (Luffy won't even let you make people cry), and their subordinates would follow their example. Ruthlessness, plundering and pillaging comes with being a pirate, but there's nothing to gain from killing just for the sake of it, you know? And that's really what makes them the 'good guys', in a way.

Also, please don't hesitate to tell me if you think i'm setting the pace too fast, if i suddenly launch into something vague and making unclear explanation of the situation, etc. I'm still wavering between following some canon in regards of how merfolk work and some story aspect, so please understand if you do spot something like that and tell me so i can improve it.

Anyway! Thank you so much for reading and i hope you liked it!


	4. Chapter 4

Shekilaria made me a fanart (i'm so giddy saying that every time like, my fics have fanarts guys! can you believe it?!) and it's super cute! I cannot link it here in FF, but i have it up on the one i posted on Ao3, so please check it out there? How do you usually put links in this site?

I had a friend of mine read little early bits of this and was like 'wait a sec, isn't this[SPOILER] don't tell me that[EVEN LARGER AND A 70% ACCURATE SPOILER]' and her explanation led me to believe that yes, some people might already figure out the twist at this point, but hey.

Just... just enjoy it as it is please, i know i'm not the most creative person out there.

Hope you'd enjoy!

* * *

The sight of legions of troops leaving Castle Oro Jackson caused anxiety across the entire city of Raftel, adding to the already tense atmosphere across the underwater metropolis.

Prince Ace, beloved son of King Roger and Queen Rouge, has been missing for over a week.

Roger saw the last of his officials and generals scramble out of the meeting room, face stormy and expression extremely dour, a reflection of his inner turmoil. Nothing, no one has found a single trace of Ace, not one caught sight of anything, no one can find his son. With heavy arms, he lifted himself off from the throne, his long, blood red tail twitching ever so slightly as he floated back and fro. Where could he be?

"We need to widen the scale," he muttered finally, wringing his hand behind his back, "Search all across the seas, have more people sent out. Turn all stone, interrogate even the smallest, newly hatched guppy, there has to be _something,_ "

"Roger, we already sent out everyone," The only person left in the room, his advisor reminded him, his own moss green and ground coloured tail giving a single wave until he stood next to his king from where he sat, "It's been a week, he must've gone far. Perhaps, he might even have reached—"

"No! No, he can't possibly find a way to cross the currents, Rayleigh," the king stressed out, gritting his teeth, even though he knew the merman has a point. Where else could Ace had possibly gone to? He's always been a curious one, and added with his daredevil attitude, it never bode well, "Not to mention, he won't be able to find a way to get pass The Gate,"

Silvers Rayleigh pursed his lips and folded both of his arms, staring grimly at his king as he muttered lowly, "You know that sea king is far more loyal to Ace, than he is to you. Or did you forget _what_ he is?"

How could he? It was the entire reason he was this panicked, why he had done all of these security countermeasures to keep him in the castle, all for nothing. The dark haired king gritted his teeth with an intense frown, waving his advisor off with a jerky motion, "Send some of the troops to the end of the sea and check for any clues of the prince's whereabouts. Use any measures necessary to find him. Post rewards for any information, triple— no, _quadruple_ the amount for anyone who managed to find him and bring him back. I want my son back home, save and sound," And with that, he floated away out of the room, leaving the advisor to sigh glumly at his retreating back.

The king would usually be full of smiles to anyone he passes by, but today, just like the last few, none of the servants or soldiers dared to approach him. They merely bowed a little as he passed, not given enough time to utter a single word as he rushed to the end of the eastern wing of Castle Oro Jackson. The deeper he came, the more the lack of people becomes apparent, and he swore that the moment Ace returns home, he'll have this entire hall and the grounds outside of it to be filled with guards.

The very last room on the hall, the one with the biggest and most ornate door was ajar, and the moment it came to sight, Roger slowed down, chest heavy and his breathing stuttering. Quietly, he floated to the stone gate, lips downturned and all anger or anxiety washed into nothing but sorrow. He pushed the door quietly, weakly, revealing the room that for the first time in so many years, was missing its owner. Fully furnished, fully equipped with anything anyone could possibly want, full of personality and comfort, and yet it still failed compared to the world outside.

On the large, plush bed, he found Rouge sitting on the middle of bed made out of the finest coral and covered by soft algae, looking distantly outside of the looming window right next to the bed. It held the most magnificent view of the entire Raftel, overlooking the most flourishing part of the city. Quietly, the king made his way over, sitting on the edge of the bed without a word.

"Maybe this is our punishment," after a long bout of silence, he finally heard the queen said quietly, voice distant, "For trying so hard to defy fate,"

Roger's face scrunched up in displeasure, "We're parents who wanted to protect our son. There's nothing wrong in that,"

A hand was placed on his muscled shoulders, and the turned to find Rouge's tear-welled eyes looking down at him, irises only a shade darker than her hair reflecting his own face at him, "Look what that achieve, Roger," she told him sadly, "My baby, _our_ baby is now out there, unprepared, all alone, and anything could happen to him. He didn't know the danger, didn't know what could be waiting for him out there,"

"We'll find him, Rouge," he cradled the mermaid's delicate hand between his own larger ones, but right now, as they trembled, they didn't feel any less fragile than hers, "Nothing will happen to Ace. We'll find him and bring him back here, and everything will go back to normal,"

But Rouge's face didn't look relieved or convinced, and Roger knew his own belief of his words were shaky at best, "It won't," her words were soft but the impact it had on Roger's painfully clenched chest was immense, "You know what he is after. You know he'll find out what we've been hiding from him for all of his life. It was always going to happen, Roger, no matter what we did to prolong this, we know it's inevitable," she pulled her hand back, before framing the side of his face, focusing his sight to her, "It's always been our son's destiny,"

He tried to find a word to assure her - and himself - to deny the dawning realization that he knows she's telling the truth. But he can't.

Roger stays silent as Rouge pulled him in an embrace, one hand clutching hard at his missing son's cold, empty bed sheets.

* * *

"I hope you know this is the very opposite of sneaking,"

"Pfft, what are you talking about, we are totally unseen!"

"…No, no we are not,"

Luffy pursed his lips, taking in the lack of any recognizable paraphernalia that might identify him as a general and noble's son, his casual float that won't attract attention and the seaweed hood he had over his strawhat to conceal the unusual thing. In the end, he shrugged, "What? We're already blending in. Or, Zoro, do you mean your swords? I told you we don't need them,"

Defensively, the green haired merman next to him clutched the three swords strapped by his side, scowling, "No, stupid, i'm talking about _that,_ "

"Whaaaat? You mean the food in the bag? But we'll need them! The journey to the human waters would be really long, remember?"

"That bag is easily four times your size and it's blocking the entire road! And stop saying our destination so loudly, damnit, you're the one who wanted to be discreet with this shrimpbrained idea!"

"It's not a shrimpbrained idea! We're going to save Ace!"

And wanting to save his brother and take him back home is not stupid. He'd seen how stressed out King Roger and how sad Queen Rouge was about this entire thing, and not even his dad's best man can seem to find him. Ace had always been really good at disappearing once upon a time, before he was always trapped inside of his room and never allowed to leave, "Do you think it's because Ace got bored staying in his room every day? I think it's been over 12 years since he can go outside and play anymore,"

He has been quite young when it all happened. He, Ace and Sabo had been going on as usual, exploring Raftel from corner to corner, until Ace decided that they're old enough to go beyond the borders and see what is outside of the city itself, something they were all always warned against by their elders. But they did anyway, and nearly got caught by evil mermen who lurked outside of the city. They recognized Ace as the prince and him as General Dragon's son, and had wanted to capture them for ransom.

What followed had always been fuzzy at best, but Luffy remembered being caught by one of the mermen, his fin and tail not strong enough to make him swim faster than adults. Ace and Sabo tried to free him, and were almost caught too if it wasn't for the Sea Kings who suddenly appear out of nowhere to save them.

King Roger and his army, including his dad came not long after, and Luffy could still remember the king's ashen face, looking fearfully at the Sea Kings that guarded the three of them from the running would-be kidnappers. He wouldn't listen to them saying that the Sea Kings came to help them, and the day after, he was told that Ace can no longer go outside.

He thought that it had been a punishment for them venturing out beyond the border and going against what they're told not to do, since Grandpa Garp had grounded both him and Sabo. But days becomes weeks and week becomes months, and suddenly, Luffy barely ever see Ace outside again. He was always trapped in his bedroom, looking sadder and angrier every passing day until he just finally seems to accept it.

He never did understood why. As year passed, Sabo became a scholar and his dad's right hand man to lead some some super secret army made by the king that he can't even tell Luffy, while Luffy would gain a lot more friends and goes on adventures all around the sea.

But Ace? Ace was always trapped in his room, day in and day out, unable to leave.

"Probably. As nice as his room may be, it must be suffocating and lonely to be locked in one place for such a long time. It might as well be a gilded cage,"

Luffy let out a soft and sombre hum, "Yeah, but even though he's free now, he's still out there all alone, like he always was and that's sad. That's why we have to find him quickly, so he won't be anymore,"

* * *

"What is that?! That's so cool!"

With how dark their surrounding has become, the bright shine of the fire made it look like Ace's eyes were shinning even brighter than they were supposed to in his wonder. The darker grey tone of his eyes seems to lit up, and faded once again as the merman finally looked away from the newly lit bonfire to Marco, face eager and demanding at the same time, "What is that? What do humans use it for? Why is it… Oh! Oh, it's exuding something! I've never seen anything like this before, it… it feels different, like the surface of the waters here at day time,"

Before Marco can say anything, he suddenly shot out a damp and clawed hand out of the water to reach towards the bonfire. It was only the blonde's quick reflexes that managed to stop him, "No, no, don't touch it, it burns,"

"Burn? What's that?"

"It's…," With a sigh, he turned from Ace to look at the fish gathered around the merman's tail on the shores, the likes of barramundi, carps and trouts still staring up at him. Marco proceeded to look away.

He had been reasonably weary when Ace had frowned at him the moment they landed on this small islet to rest for the day, and true enough, the young merman had said something about a message for him from the fishes that follows and appear on their journey. It would seem that his refusal to consume them lately has offended the nearby ecosystem, who felt like their willing sacrifice was all for naught and even took it as an insult to the care they took to grow healthily for the prince and his pet avian's sake.

Marco didn't know what he is more confused about; the fact that not eating these very aware and very intelligent beings made him more guilty then eating them, or the fact that apparently, to fishes and whatever other sea life there is, he is now only known as 'the prince's pet avian'.

Well, he supposed he had been called worse things by worse people before.

Which was the reason for the bonfire in the first place. They're nearing the colder part of the seas, something that he wasn't particularly fond of, and despite being a zoan, he didn't exactly fancy eating raw fish every single day until the end of this chase. But the moment he lit up the little sticks and branches he had gathered, Ace immediately had bombarded him with a millions of question, while staring at the fire as if it was the most fascinating wonder he had ever come across in his life.

Then again, for someone who spent their entire life under water, fire probably is a fascinating wonder.

The more the day passed, the more like there doesn't seem to be an end to the difference between their species. Just yesterday, he caught Ace lying on the beach of the island they rested on, obviously sleeping and unaware of the small fishes that crowded and nibbled on his skin. Fearing the worst, Marco had shooed the fishes away, until Ace told him that it was how merfolk cleaned themselves, letting these little fishes feast on whatever parasite and algae that covered their body after swimming for so long.

Seems like today it was Ace's turn to be bedazzled by 'human wonders', which is a direct improvement from every other heart attack inducing mer behaviours he had Marco witness, "So this is what a 'fire' look like. So it's hot? And what's 'cook'? You're not going to disrespect the fishes even more, are you? One of the barramundi's sister in law is friends with a hammerhead shark and he said they're going to teach you a lesson and drown you if you do,"

"I'm— what?" Marco could only blink and shook his head once he decided those string of sentence made no sense and thus indigestible, turning to the bonfire once more to keep stoking the flame, "And, it's not… disrespectful to the fishes. I think. I'm just going to cook the fish so it won't have any bacteria and healthier for a human like me to eat,"

"You're calling them dirty?! I knew it was another insult!"

"No! It's… ugh, just let me show you,"

He picked up one of the fishes and after a quick and mumbled gratitude, slammed their head on the nearest rock as he was taught to do. The commander then picked up one of the thinner stick and the dagger he had stolen from the pirate ship days ago, slitting out the stomach and taking out the insides, cleaning its gills and scales, before stabbing the fish through with the stick and stabbing the other end of the stick on the ground, close enough to let it be roasted over the fire.

"Now what?"

"Now we wait until it's cooked,"

It didn't take that long, but in his impatience and hunger, Ace already began eating, starting on the trouts who lined up next to him even though his eyes never left the one near Marco's fire. He stopped munching by the time the human picked the stick out from the ground, presenting the now smoking and discoloured fish to his merman companion, "And now the fish is cooked. Careful, it's still hot,"

Not that Ace seems to care or even affected, as he pinch out a flaky part from the cooked fish's side, staring open mouthed wonder - that shows bits of chewed raw fish meat - at the now more tender meat and even crispy skin. He put that little bit into his mouth, and immediately widened his eyes while started blowing out with squeezed eyes, obviously unable to handle the heat on his tongue. Marco shook his head and chuckled, somewhat amused, "I told you it's hot,"

But despite his little jab, the merman still swallowed, and the zoan watched as those grey eyes blinked a couple of times before turning back to him, eyes even wider so and grinning, "That.. that was amazing!"

"I'd say cooked and cleaned fish does taste better than raw, yeah,"

"Cook all of these guys!"

"Yeah i— what?"

"Cook them! I want to eat them cooked from now on! Come on, cook them, cook them!"

The fished started making bubbling noises underwater, somewhat adding to the urging.

"I… there's dozen of them down there!"

"Then start cooking now! Come on, Marco, i'm hungry and i wanted to eat more of that!"

What had he done?

What had he done to himself?

* * *

"Any changes on Poseidon and Teach's location?"

In the midst of eating the last of his roasted fish - courtesy of Marco's thankless hard work - Ace's eyes flickered away from the fire he had been staring at intently, his gaze turning distant yet focused, "None, Poseidon is still in the same place as before,"

Marco gave him a noncommittal hum as he sat by the dry patch of land close enough to the waters, staring at the log pose in his hand with the help of the bonfire and the moonlight.

It's been 5 days since he continued his journey with Ace in tow, and if his observation was correct, the merman seems to be leading them away from Grand Line and towards East Blue, claiming that Teach hadn't moved at all. And from the newspapers he snatched from a randomly passing Coos this morning, there hasn't been any news of Teach's location or next movement, and he's not sure whether or not this is a good thing. Teach surely has a plan, doesn't he? Wherever he was, Marco would imagine he's trying to gather his crew before making his way back to Grand Line and into New World.

Still, if there's anything Marco knows about him - which apparently, not much, he thought bitterly - was that Teach was quite intelligent. He should know that staying in one place when he's wanted by a _Yonko crew_ is a bad idea, and while he might also had moments of laziness, it doesn't make sense why he would be wasting so much time hiding.

Various scenarios appeared and was disproved in his own mind, and the blonde only shook his head. He can't help but to think there's something obviously wrong, and he hated that he won't know what it is until they caught up with the bastard.

Is it possible that Teach has abandoned Poseidon somewhere and he's continuing on a wild goose chase? After all, he's been following Ace presuming that Teach would be with his stolen treasure.

Actually, what exactly is this Poseidon? Considering it can be stolen, it couldn't be one of the poneglyphs, unless he somehow found a way to unearth those enormous slabs of rocks and carry it with him, but that raised even more questions. Poneglyphs are the only thing known to them that has anything to do with One Piece and Raftel, so how did Teach even know it's also related? It can't be a mere coincidence, can't it? Him accidentally finding the merfolk's territory because of storm is one thing, but Teach leading an attack to what sounds like a well guarded sanctuary has to be a well calculated plan.

And how did Teach even know about it when the merfolk's own prince were entirely clueless to what it is?

"Hey, can i ask you something?"

"Hmm? Sure, what is it?" Ace narrowed his eyes, and turned his body away from where Marco laid, "I'm not sharing the cooked fishes. You said yourself that you're already full,"

"No, i'm not asking for your food," the blonde suppressed the need to sigh out loud, "I just wanted to ask, but you said you were kept sheltered your entire life, right? Weren't you at least taught about how your own kingdom works though? Don't you have lessons and stuff about how to run a kingdom, the important artefacts and treasures like One Piece or this Poseidon we're chasing after?"

At his question, Ace grew somber, lips downturned and he even put his food down. The dark haired merman sighed, "I'm not allowed to. No one ever told me why, but i was always told to stay in my room. I barely ever meet anyone aside from my parents, Ray, and Sabo and Luffy. My parents never told me anything about what's going on outside, Ray only taught me basic stuff and not much about the kingdom or the people, and Sabo and Luffy couldn't too. When i sneaked out, it was the first time in 12 years that i saw Raftel up close, and it has changed so much. It didn't seem to change at all from my windows,"

"You have any idea why?"

Ace shook his head, brows furrowed in irritation that doesn't seem to be able to muster enough strength into anger, "I know i'm clueless about a lot of things, but even i know that being kept in that place for so long, even though i always have servants at my disposal and all of my needs met, that's not living, you know? I miss swimming from one side of Raftel to the other, i missed talking to others, i never get to travel like i always wanted when i was young. I'm the prince, but i know nothing about the world i could only see from my window,"

It's hard to think that this free spirited being was ever kept locked in - 12 years? That's almost like a lifetime to be kept in one single room - and as curious as Marco was as to why, he didn't think he'd get the answer out of Ace, "Well, you're here now, even further away from your kingdom,"

The dark haired merman nodded, "I know, but once this journey ends and i have to take Poseidon back home, i will have to go back to that room again, trapped in and could only see the world outside from that damned window. I…," he took a deep breath, and muttered in a small voice, "I don't want that,"

In the span of few days, Marco had seen a lot of sides of Ace, but this one, this sad, gloomy one seems like a reflection of what he looked like for the last 12 years being a captive in his own kingdom, his own home. As a pirate, as someone who lived his life freely in the seas, whose entire life was based on freedom, Marco couldn't imagine what it's like to be him. Or he did, but it was such a distant memory that he shuddered thinking about it, let alone imagining someone else in that position of helplessness and the feeling of being stuck.

But he couldn't think of anything to say to make things better, so in the end, he simply said, "Well, it's not like we're nearing the end of this journey, i think we barely even begun. Don't think about having to come back just yet and enjoy what you're doing now. Think of it this way, you're probably the first merman in centuries to ever venture outside of your own territory, and right now, you have more knowledge than the entirety of your kingdom about what's outside their kingdom,"

He smiled, wider still when Ace glanced up to him with a considering look, "Hell, you're probably the only mermaid in centuries who knows what's a fire and why it burns. Think of this as your turn to explore these human shores, out from your seas," he motioned to the sky, blue eyes never leaving Ace's darker ones, "A part of this world,"

Ace kept quite, but when he does speak, a small smile finally bloomed on the merman's face, a beatific and gentle one that caught Marco genuinely off guard, "You're right, Marco. Thank you,"

The blonde decided that even with the smattering bits of fish meat around his teeth and lips, it was a good look on him.

* * *

There's a reference there somewhere at the end. Please tell me you get it, and tell me off if you think it's too cheesy.

Because i did. But i'm not gonna delete it because of how proud i am of it.

Thanks for reading!


End file.
